Take into account that don't assume all people living in China are necessarily Chinese. It is often displayed in various regions that distinctive groups had their particular distinct culture. China was not always unified. It turned out many different tribes/countries some time before unity ever occurred and unity wasn't always stable (such as several Kingdoms, the Warring States Period, the relocation of the Sung dynasty after Beijing fell to invaders). For instance, the town of Chongqing, a long time before it became annexed into Imperial China had its own culture along with perhaps a language also. The mountainsides of Chongqing has carvings of fierce pagan gods non-existent in mainstream Chinese culture. An original Chongqing citizens were also primarily decimated because of war therefore the Emperor necessary a migration to the present region. Its likely which the Emperor called for migration with regions thus cultures mixed together until they became made available to the Chinese or were destroyed with the Chinese. If you take a look at a map of the Qin Dynasty, the region which is now Guangzhou province remains unclaimed. Usually are not lived there? Its likely that there were independent tribes surviving in this region. And later in Chinese history, the Chinese people migrated into this region, mixing while using original people, thus eliminating their cultural identity. One more thing to mention, when you look at records on the earlier dynasty including the Xia, Shang, and Chou, each of them existed in the northern regions, not southern.